Charge chutes for atomic reactors



March 29,- 1960 A. SHILLITTO ETAL CHARGE CHUTES FOR ATOMICREACTORS Filed Dec. 17, 1956 United States Patent O CHARGE CHUTES FOR ATOMIC REACTORS Arthur Shillitto, Dennis Michael Watts, and Kenneth Arthur Billingham, Whetstone, near Leicester, England, assignors to The English Electric Company Limited, London, England, a British company Application December 17, 1956, Serial No. 628,777

Claims priority, application Great Britain December 23, 1955 4 Claims. (Cl. 204-1932) This invention relates to charge chutes for loading and unloading the fuel elements of an atomic reactor of the kind in which the fuel elements are disposed within a pressure vessel in vertical fuel channels spaced transversely from each other.

It is known to refuel such reactors by means of a charge chute which incorporates at its lower end a fuel element guide member pivotally mounted for angular movement relative to the axis of the chute whereby to bring the end of the guide member over any one of a number of fuel element channels associated with a particular charge tube.

In such an arrangement the guide member must always be at an angle both to the axis of the fuel element channels and to the axis of the charge tube except, of course, when it is being inserted through the charge tube. This of necessity means that the fuel elements have to move through a path which includes twosudden angular changes of direction and, since the fuel elements themselves are of considerable length the guide member and the charge chute have to be increased in diameter in order to allow the fuel elements to change direction without fouling on the inside of the charge chute.

One object of the present invention is to provide an improve charge chute which does not involve this sudden angular change of direction of the fuel elements.

According to the invention in a charge chute for an atomic reactor of the kind including a movable fuel element guide member at the lower end of the chute, the guide member is of sufficient length to accommodate at least one fuel element and is mounted on the chute for movement from a position in axial alignment with the chute to at least one position in which its axis is spaced from and lies substantially parallel to the axis of the chute.

In such an arrangement, after the chute has been inserted into the reactor, refuelling is carried out by lowering a grab head through the chute into the guide member which is then moved to the spaced position, this position being arranged to coincide axially with a fuel element channel. The grab head is then lowered into the fuel element channel, caused to grip a fuel element and then raised until the fuel element lies completely within the guide member. The guide member is then moved back to its axially aligned position and the fuel element is finally withdrawn through the charge chute. The reverse sequence is carried out for loading new fuel elements into the fuel element channels.

According to a preferred feature of the invention, a further guide member, also of sufficient length to accommodate at least one fuel element, is articulated at its upper and lower ends to the chute and to the upper end of the first mentioned guide member respectively, the first mentioned guide member being further arranged for movement either to a position in which both it and the further guide member are in axial alignment and are disposed at an angle to the axis of the chute, or to a position in which its axis lies at an angle to the axis of the further guide member, the axis of the further guide member then coinciding with the axis of the chute.

The accompanying drawing shows diagrammatically at Figs. 1 to 4 a preferred form of charge chute according to the invention, Figs. 2 to 4 being enlarged views showing the lower end only of the chute.

Referring now to Fig. 1, the charge chute, generally indicated at 10, is inserted into the reactor through the access tubes 11, only one of which is shown in this figure. Each access tube 11 services a number of fuel element channels in the reactor core 14, only two channels 15 and 16 being shown in this figure.

As shown most clearly in Figs. 2-4 the charge chute comprises a tube 17 which over its lower portion is approximately U-shaped in section and in this lower portion are mounted two further tubes 18 and 19 which, with the chute in the attitude shown in Fig. 1, fit snugly into the lower portion of the tube 17.

The tube 18 is attached to the tube 17 by means of pivot pins 20 and to the tube 19 by means of pivot pins 21. A link 22 is attached to the tube 17 by means of a pin and slot connection 23 and to the tube 19 by means of pivot pins 24. A further link 25 is coupled to the tube 17 by means of a pin and slot connection 26 and to the tube 19 by means of pivot pins 27. A projection 28 at the lowermost end of the tube 17 engages a locating hole 29 opposite the access tube 11 so as to locate the charge chute in position.

The links 22 and 25 are arranged to be moved in the pin and slot connections 23 and 26 respectively by means of push rods 31 and 32 coupled at the lower ends thereof to the pins of the links. These push rods extend upwards through the tube 17 for operation from a position outside the biological shield 12.

The charge chute is inserted in the access tube 11 in the attitude shown in Fig. 1 and is located in position by entering the projection 28 into the locating hole 29. To extract a fuel element 30 from the channel 15, the push rods 31 and 32 are actuated so as to set the tubes 18 and 19 to the attitude shown in Fig. 2, in which attitude the tube 19 is positioned in vertical alignment with the fuel element channel 15. A fuel element grab head, having jaws arranged to grip the upper end of the fuel element, is then lowered through the charge chute into the channel 15 and the fuel element 30 is withdrawn upwards until it is housed completely in the tube 19.

The push rods 31 and 32 are then actuated so as to set the tubes 18 and 19 to the attitude shown in Fig. 3 and the fuel element 30 is further withdrawn upwards until it is housed entirely within the tube 18. Finally push rods 31 and 32 are actuated so as to set the tubes 18 and 19 to the attitude shown in Fig. 4 and the fuel element 30 is then withdrawn completely from the charge chute.

From the foregoing it will be appreciated that at no time is the fuel element pulled round a corner, i.e. there is no sudden angular change in the direction of movement. No bending stresses are therefore applied to the fuel element.

To withdraw fuel elements from the channel 16, which is on a larger pitch circle than the channel 15, the charge chute is merely rotated to the correct angular position and the push rods actuated to move the tube 19 into vertical alignment with the channel.

The reverse sequence is carried out for loading new fuel elements into the fuel element channels.

In an alternative procedure, after a fuel element has been withdrawn upwards from the reactor core into the tube 19, the charge chute is set directly to the attitude shown in Fig. l.

The charge chute according to the invention may, of course, also be used for refuelling liquid moderated re actors.

Any convenient mechanism may be used for actuating the push rods 31 and 32 from a position outside the biological shield.

What we claim as our invention and desire to secure by Letters Patent is:

l. A charge chute for inserting and withdrawing the fuel elements of an atomic reactor of the kind in which the fuel elements are disposed within a pressure vessel in vertical fuel channels spaced transversely from each other comprising, in combination, a main tubular guide member arranged to be inserted vertically downwards into said pressure vessel, an auxiliary tubular guide member at the lower end of said main guide member, the diameter of both guide members being such as to allow free passage of a fuel element therethrough and the length of said auxiliary guide member being sufficient to accommodate at least one fuel element, axially spaced link means interconnecting said auxiliary guide member and said main guide member so as to allow movement of said auxiliary guide member between a position in axial alignment with said main guide member and a plurality of positions substantially parallel to but spaced transversely from said main guide member, whereby the auxiliary guide member may be moved into vertical alignment with a corresponding number of fuel channels, and actuating means extending upwards through said main guide member for moving said auxiliary guide member from a position outside said reactor.

2. A charge chute for inserting and withdrawing the fuel elements of an atomic reactor of the kind in which the fuel elements are disposed within a pressure vessel in vertical fuel channels spaced transversely from each other comprising, in combination, a main tubular guide member arranged to be inserted vertically downwards into said pressure vessel, two articulated tubular guide members at the lower end of said main guide member, the diameter of both said main guide member and the two articulated guide members being such as to allow free passage of a fuel element therethrough and the length of at least the lowermost of said two articulated guide members being sufficient to accommodate at least one fuel element, axially spaced link means interconnecting said lowermost articulated guide member with said main guide member so as to allow movement of said lowermost articulated guide member between a position in axial alignment with said main guide member and a plurality of positions substantially parallel to but spaced transversely from said main guide member, whereby said lowermost articulated guide member may be moved into vertical alignment with a corresponding number of fuel channels, and actuating means extending upwards through said main guide member for moving said lowermost articulated guide member from a position outside said pressure vessel.

3.A charge chute for inserting and withdrawing the fuel elements of an atomic reactor of the kind in which the fuel elements are disposed within a pressure vessel in vertical fuel channels spaced transversely from each other comprising, in combination, a main tubular guide member arranged to be inserted vertically downwards into said pressure vessel, two articulated tubular guide members at the lower end of said main guide member, the diameter of both said main guide member and the two articulated guide members being such as to allow free passage of a fuel element therethrough and the length of at least the lowermost of said two articulated guide members being sufficient to accommodate at least one fuel element, pivotal mounting means connecting the upper end of the uppermost articulated guide member to said main guide member for angular movement of said uppermost articulated guide member relative to said main guide member, upper and lower link members connecting said lowermost articulated guide member to said main guide member, pivotal connecting means connecting each of said link members to said lowermost articulated guide member for relative angular movement therebetween, pin and slot connection means connecting each of said link members to said main guide member for angular and sliding movement of said link members relative to said main guide member, and actuating means extending upwards through said main guide member for moving said pins in said slots from a position outside said pressure vessel so as to cause movement of said lowermost articulated guide member between a position in axial alignment with said main guide member and a plurality of positions substantially parallel to but spaced transversely from said main guide member.

4. A charge chute for inserting and withdrawing the fuel elements of an atomic reactor of the kind in which the fuel elements are disposed within a pressure vessel in vertical fuel channels spaced transversely from each other comprising, in combination, a main tubular guide member arranged to be inserted vertically downwards into said pressure vessel, two articulated tubular guide members at the lower end of said main guide member, the diameter of both said main guide member and the two articulated guide members being such as to allow free passage of a fuel element therethrough and the length of both articulated guide members being sufiicient to accommodate at least one fuel element, pivotal mounting means connecting the upper end of the uppermost articulated guide member to said main guide member for angular movement of said uppermost articulated guide member relative to said main guide member, upper and lower link members connecting said lowermost articulated guide member to said main guide member, pivotal connecting means connecting each of said link members to said lowermost articulated guide member for relative angular movement therebetween, pin and slot connection means connecting each of said link members to said main guide member for angular and sliding movement of said link members relative to said main guide member, and independent actuating means extending upwards through said main guide member for moving said pins independently in said slots from a position outside said pressure vessel so as to set said articulated guide members either to a position in which they lie in axial alignment with said main guide member, a plurality of positions in which said lowermost articulated guide member lies substantially parallel to but spaced transversely from said main guide member, and, for each of said plurality of transversely spaced positions, to set both articulated guide members in axial alignment with each other and at an angle to said main guide member, or the uppermost articulated guide member to a position in axial alignment with said main guide member, with the lowermost articulated guide member at an angle thereto.

OTHER REFERENCES Nucleonics, vol. 14, No. 12, Dec. 12, 1956, pp. 522-523. 

1. A CHARGE CHUTE FOR INSERTING AND WITHDRAWING THE FUEL ELEMENTS OF AN ATOMIC REACTOR OF THE KIND IN WHICH THE FUEL ELEMENTS ARE DISPOSED WITHIN A PRESSURE VESSEL IN VERTICAL FUEL CHANNELS SPACED TRANSVERSELY FROM EACH OTHER COMPRISING, IN COMBINATION, A MAIN TUBULAR GUIDE MEMNER ARRANGED TO BE INSERTED VERTICALLY DOWNWARDS INTO SAID PRESSURE VESSEL, AN AUXILIARY TUBULAR GUIDE MEMBER AT THE LOWER END OF SAID MAIN GUIDE MEMBER, THE DIAMETER OF BOTH GUIDE MEMBERS BEING SUCH AS TO ALLOW FREE PASSAGE OF A FUEL ELEMENT THERETHROUGH AND THE LENGTH OF SAID AUXILIARY GUIDE MEMBER BEING SUFFICIENT TO ACCOMMODATE AT LEAST ONE FUEL ELEMENT, AXIALLY SPACED LINK MEANS INTERCONNECTING SAID AUXILIARY GUIDE MEMBER AND SAID MAIN GUIDE MEMBER SO AS TO ALLOW MOVEMENT OF SAID AUXILIARY GUIDE MEMBER BETWEEN A POSITION IN AXIAL ALIGNMENT WITH SAID MAIN GUIDE MEMBER AND A PLURALITY OF POSITIONS SUBSTANTIALLY PARALLEL TO BUT SPACED TRANSVERSELY FROM SAID MAIN GUIDE MEMBER, 